Hydrocarbon fluids such as oil and natural gas may be obtained from subsea wells. Subsea test trees enable well testing and well cleanup operations to be conducted on subsea wells from an offshore floating rig. In the event the well is to be shut down, the subsea test tree includes valves for shutting in the well and for preventing discharge of the landing string contents into an associated riser. The subsea test tree also comprises a latch mechanism for safely disconnecting the landing string.